Polling began on Wednesday morning at the key Budhni assembly constituency in Sehore district, where Madhya Pradesh Chief Minister Shivraj Singh Chouhan is contesting as a Bharatiya Janata Party nominee.

In a 16-cornered contest, Chouhan's chief rival is Congress candidate Rajkumar Patel -- a former state minister. Gondwana Ganatantra Party nominee Gulzar Singh Markam, who is also his party's state chief, enjoys the support of Bharatiya Janshakti Party president Uma Bharati, who was expelled from the BJP.

About 1.74 lakh people, including 82,498 women, are expected to exercise their franchise through Electronic Voting Machines in 189 polling stations, 80 of which have been proclaimed as sensitive.

Elaborate security arrangements are in place within the sprawling rural constituency spread over more than 350 villages with deployment of two Central Reserve Police Force and four RAF battalions besides district police.

Budhni fell vacant after Rajendra Singh (BJP) resigned to pave way for Chouhan's entry into the assembly. The counting of votes will take place at Sehore on May 6.